This invention relates to a stabilizer arrangement for use in downhole drilling applications.
Subterranean boreholes commonly extend underground for great distances and are often formed using steerable drilling systems with the result that the direction thereof may change significantly over the length of the borehole. The loadings experienced by the drill string used in the formation of such a borehole, during rotation thereof, are large and in order to reduce drag, and allow cuttings from the formation to pass up the borehole to the surface, the drill string is typically smaller in diameter than the borehole so as to provide some annular clearance around the drill string and allow contact between the dill string and the borehole wall to be kept to a minimum. Stabilizers are used at intervals along the length of the drill string in order to stabilise the drill string relative to the borehole. Stabilizers are also commonly used, for similar purposes, in the bottom hole assembly including adjacent to the drill bit.
Stabilizers are described in, for example, U.S. Pat. No. 1,721,004, U.S. Pat. No. 3,945,446 and U.S. Pat. No. 4,456,080 in which in addition to providing a gauge surface which, in use, bears against the wall of the borehole in which the stabilizer is used, also define flow passages to allow fluids to continue to flow along the borehole.